Zeus 80 – Restored and working

After a full disassembly, inspection and cleaning, the Zeus 80 fired right up. I

Zeus 80 – front

used an 8″ CP/M 2.2 boot disk and booted the machine and ran Adventure! I am very happy to have found this and acquired it because of it’s Canadian heritage.

Many of the internal cards appear to be similar to SD Systems cards but the Z80 MPU card is manufactured or branded by CTM (Computer Terminal Maintenance LTD) that is also the manufacturer of the Zeus 80 computer.

The keyboard also needed work. Not one key worked I was a little worried that it might be the keyboard circuitry, depending on how the keyboard was made. I was very happy to find that it was a Keytronics keyboard with foam pads

Zeus 80 – Keytronic keyboard internals

similar to some of the other systems of that era including the Apple Lisa. After a few decades, the internal foam disks turn to goo or dust and the myler coating on the pads wears out. Essentially, all of the keyswitch foam pads failed. In addition, the keyboard circuit board required some cleaning because it gets dull. This was cleaned with a white rubber pencil eraser that is not rough but the friction and sticky rubber removes any residue on the keyboard contacts. It’s safer than removing the surface layer with high grit sandpaper.

In this computer, the 8″ drives are a little noisier that I’d like but they function

Zeus 80 – internals

properly. The heads were cleaned and when I get some more time with the system, I’ll lubricate the drives properly. The screen was collapsed to about 1/3 of the 12″ monitor height. This was adjusted via some of the pots on monitor circuit board. Unfortunately, I didn’t have a schematic to figure out where to make the adjustments so I had to do so by trial and error. It worked out fairly well but I have some “roll over” on line 1 of the output. I’ll leave it at that for now.

Below are the four internal cards in the six slot S-100 card cage. These cards

Zeus 80 – S-100 internal card cage

have model numbers hand written on them but other than the CTM MPU card, they don’t have a manufacturer ore model numbers printed on them. I recognized the memory card as being an SD System ExpandoRAM II card and looked at the rest of the SD Systems cards at http://www.s100computers.com and found the video and floppy controller cards were SD System cards as well.

In my research, I could find nothing about this computer other than a “Zeus 80” trademark application posted by the Canadian government. Once I knew the manufacturer, I was able to dig deeper. I was able to find a version of

Zeus 80 – Serial number plate

the CTM MPU-8011 card at Dave Dunfield’s site under CompuDuct/CTM S-100 cards. I also found reference to a CompuDuct Rainbow at Dave’s site that looks almost identical to the Zeus 80 chassis but the keyboard is different and the S-100 cards are different (must be the ones he listed under CompuDuct/CTM above). He has a picture of the serial number plate and it’s clearly different from the Zeus 80. These must have been rebranded by one company or the other with both companies being within walking distance in Markham, Ontario

7 Responses

I have quite a lot of documentation for the Zeus80/Rainbow (same computer, different business owners). Schematics, user manual, technical manual, ROM listings (the video card has non-SD Systems code to speed it up). The later CPU card allowed up to 7 or 8 users to share consoles and printers when running MP/M-80 (multi-user/multi-tasking OS allowing CP/M-80 software to execute). It was sold in Canada, Germany, USA, UK and Australia, perhaps elsewhere as well. Need any documentation?

That’s terrific that you’ve cleaned it up! This was the computer that you goth from my father. I grew up with guy. I think we’re pretty much the same age. He was a consistent part of my life. Glad to know he’s gone to a good home.

I found this post very late but I’m happy to see it. Compuduct of US purchased the Canadian manufacturer but couldn’t make a go of it after IBM entered the desktop space. All manufacturing stayed in Canada. I worked for Compuduct right out of college and I’m the son of the owner (now deceased). I visited the Canadian plant and was able to meet some of the exceptional staff. The Zuess80/Rainbow was a fantastic machine. The Rainbow name was used prior to Digital’s (DEC) use of the same name. At least one of the posted names above sounds very familiar to me. Thank you for restoring this unit! Great memories of a truly pioneering group of people.